为什么我的Web客户端上传文件code挂起？ [英] why my WebClient upload file code hangs?

问题描述

我使用VSTS 2008 + C＃+净3.5 + ASP.Net + IIS 7.0来开发Windows窗体应用程序在客户端上传文件，并在服务器端我使用一个aspx文件接收该文件。

I am using VSTS 2008 + C# + .Net 3.5 + ASP.Net + IIS 7.0 to develop a Windows Forms application at client side to upload a file, and at server side I receive this file using an aspx file.

我发现我的客户端应用程序将挂起后，单击该按钮来触发上传事件。任何想法有什么问题，如何解决？谢谢！

I find my client side application will hang after click the button to trigger upload event. Any ideas what is wrong and how to solve? Thanks!

客户端code，

  public partial class Form1 : Form
    {
        private static WebClient client = new WebClient();
        private static ManualResetEvent uploadLock = new ManualResetEvent(false);

        private static void Upload()
        {
            try
            {
                Uri uri = new Uri("http://localhost/Default2.aspx");
                String filename = @"C:\Test\1.dat";

                client.Headers.Add("UserAgent", "TestAgent");
                client.UploadProgressChanged += new UploadProgressChangedEventHandler(UploadProgressCallback);
                client.UploadFileCompleted += new UploadFileCompletedEventHandler(UploadFileCompleteCallback);
                client.UploadFileAsync(uri, "POST", filename);
                uploadLock.WaitOne();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.StackTrace.ToString());
            }
        }

        public static void UploadFileCompleteCallback(object sender, UploadFileCompletedEventArgs e)
        {
            Console.WriteLine("Completed! ");
            uploadLock.Set();
        }

        private static void UploadProgressCallback(object sender, UploadProgressChangedEventArgs e)
        {
            Console.WriteLine("{0}    uploaded {1} of {2} bytes. {3} % complete...",
                (string)e.UserState,
                e.BytesSent,
                e.TotalBytesToSend,
                e.ProgressPercentage);

            // Console.WriteLine (e.ProgressPercentage);
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Upload();
        }
    }

服务器端code：

Server side code:

    protected void Page_Load(object sender, EventArgs e)
    {
        string agent = HttpContext.Current.Request.Headers["UserAgent"];
        using (FileStream file = new FileStream(@"C:\Test\Agent.txt", FileMode.Append, FileAccess.Write))
        {
            byte[] buf = Encoding.UTF8.GetBytes(agent);
            file.Write(buf, 0, buf.Length);
        }

        foreach (string f in Request.Files.AllKeys)
        {
            HttpPostedFile file = Request.Files[f];
            file.SaveAs("C:\\Test\\UploadFile.dat");
        }
    }

在avdance感谢， 乔治

thanks in avdance, George

推荐答案

正在等候在主窗口的事件线程，所以你的图形用户界面将被冻结。

you are waiting in the main windows events thread, so your GUI will be frozen.

试试这个（使用非静态的方法，可以让你使用Control.Invoke方法，以重绘运行Windows GUI线程和免费这个线程回调）

Try this (using non static methods allows you to use the Control.Invoke method to run callbacks on the windows GUI thread and free this thread in order to redraw)

public partial class Form1 : Form
{
    private static WebClient client = new WebClient();
    private static ManualResetEvent uploadLock = new ManualResetEvent(false);

    private void Upload()
    {
        try
        {
            Cursor=Cursors.Wait;
            Uri uri = new Uri("http://localhost/Default2.aspx");
            String filename = @"C:\Test\1.dat";

            client.Headers.Add("UserAgent", "TestAgent");
            client.UploadProgressChanged += new UploadProgressChangedEventHandler(UploadProgressCallback);
            client.UploadFileCompleted += new UploadFileCompletedEventHandler(UploadFileCompleteCallback);
             client.UploadFileAsync(uri, "POST", filename);    
        }
        catch (Exception e)
        {
            Console.WriteLine(e.StackTrace.ToString());
            this.Cursor=Cursors.Default;
            this.Enabled=false;
        }
    }

    public void UploadFileCompleteCallback(object sender, UploadFileCompletedEventArgs e)
    {
      // this callback will be invoked by the async upload handler on a ThreadPool thread, so we cannot touch anything GUI-related. For this we have to switch to the GUI thread using control.BeginInvoke
      if(this.InvokeRequired)
      {
           // so this is called in the main GUI thread
           this.BeginInvoke(new UploadFileCompletedEventHandler(UploadFileCompleteCallback); // beginInvoke frees up the threadpool thread faster. Invoke would wait for completion of the callback before returning.
      }
      else
      {
          Cursor=Cursors.Default;
          this.enabled=true;
          MessageBox.Show(this,"Upload done","Done");
      }
public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Upload();
        }
    }
}

和做同样的事情在你的进步（你可以更新进度指标为例）。

And do the same thing in your progress (you could update a progressbar indicator for example).

干杯， 弗洛里安

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